Thruster, Mark III
by Penalt
Summary: The sequel to Thruster and Thruster, Mark II. Applejack has always been a little jealous of her friend, Rainbow Dash. Sometimes, it's hard for an earth pony to watch her friends fly past. But maybe, just maybe, her friend can help her achieve the dream of flight. Even if it is a lust filled dream.
1. Chapter 1

"Enter," said Spitfire to the knock on the door. A moment later, Rainbow Dash entered the office of the Wonderbolt captain. "Crash, good to see you back on your hooves."

"Good to be back on them, Ma'am," said Rainbow Dash, who by now had become used to her embarrassing nickname. "I'm really raring to get back up in the sky. I've been keeping up on the new thrusters and I'm really looking forward to giving one of the Mark II units a workout."

"Whoa, slow down there, Dash," said Spitfire. "You were laid up for seven weeks and you've only just been released by the flight surgeon. Light duty only for the next two weeks."

"But Spitfire," said Rainbow Dash. "I'm fine. Besides, I've been laying in bed for the past seven weeks watching everyone else, including the Princesses, go crazy with the thruster units. Please, you've got to let me have a unit and get back up there."

"Dash, I've always liked your enthusiasm and your love of flying," said Spitfire, taking on a tone of command. "But one thing we do not mess with are orders from the flight surgeon. He says light duty for two weeks, and I back him on that."

"Yes, Ma'am," said Rainbow Dash, disappointment in her tone and every line of her body. "Understood, Ma'am, light duty only."

"Crash," said Spitfire, in a less stern tone, "you are one of the best new Wonderbolts in a generation and it was your experimentation with the thruster units that lead to the breakthrough of the Mark II. There is no way I'm going to take a chance with your safety if I don't have to."

"Thanks, Spitfire," said Dash. "It's just that I really want to push the envelope again. Isn't there anything I can do for the 2.0 program, that won't get the flight surgeon mad?"

"Flight-wise, not much," said Spitfire. "What I can do, though, is let you head home with a pair of the Mark II's, a testing frame and whatever manuals we have. Do some ground school work on the units. Once the flight surgeon clears you for full duty, I'll clear you for any flight tests you want to try."

"I'll take it, Ma'am," said Rainbow Dash. "Sorry to sound a little whiny."

"You're a pegasus, and an elite flier who has been grounded for nearly two months," said Spitfire, as she finished filling out a requisition form for Rainbow. "Frankly, I'd be worried if you weren't chewing at the bit to get back in the sky."

"Thank you, Ma'am," said Rainbow, scooping up the requisition form and looking at the details on it. "Um, one problem. I don't have room for all that stuff at my place."

"Good point," said Spitfire. "Well, any place in particular I should put on the form to have it delivered to?"

"Have it delivered to the barn at Sweet Apple Acres, Ma'am," said Rainbow Dash, after a moment's thought. "Applejack has tons of room on her farm and lots of tools too."

"Okay, Rainbow," said Spitfire, adjusting the form to reflect the change in destination. "You are now officially on detached light duty for the next two weeks. Now, go out there and be a Wonderbolt."

"Yes, Ma'am," said Rainbow Dash, with a smile and a parade ground quality salute. Turning smartly she left the office, leaving a pensive Wonderbolt captain in her wake, wondering if perhaps she had just done something akin to sending Discord to a library.

Two days later found Rainbow Dash sitting in some tall grass with her friend Applejack, on a small hill overlooking Sweet Apple Acres. The sun was just setting, and Applejack was having some well-earned down time after a full day of taking care of her orchards. A golden glow was covering the trees, and all looked well with the world. Despite that, Rainbow heard a deep sigh coming from her earth pony friend.

"Why the long face, AJ?" asked Rainbow. "The farm looks great. You don't have to be an earth pony to know the farm is awesome this year."

"Ya, the farm is doing pretty good right now," said Applejack. "Ah was just thinkin' about you and those crates you had delivered a couple a days ago."

"The stuff from the Academy?" asked Rainbow Dash. "You know that's those thrusters and some test gear, right?"

"Ya, Ah know," sighed Applejack. "It just that..."

"It's just what?" demanded Rainbow Dash. "C'mon AJ, you're a friend. I'll never leave ya hanging."

"All my life, Ah've dreamed of flying," said Applejack. "Not in a balloon or a chariot. Ah mean really fly. Under my own power. Ah can barely imagine of how wonderful it must be for you. Ah see you up there, soaring, without a care, and Ah want some of that sometimes. It's one of the reasons Ah ride you so hard sometimes. It's not right of me, Ah know, but sometimes Ah get jealous of you."

Rainbow Dash looked at her despondent friend. Dash had been grounded for barely two months and it had almost been like torture. She took in Applejack's face and thought of what it must be like for an earth pony sometimes. Forever stuck on the ground, and forced to watch others fly by. As Rainbow Dash sat and studied her friend came to a decision.

"C'mon AJ," said Rainbow Dash. "If you're willing to put yourself in my hooves I think I might be able to give you the sky."

About ten minutes later the pair were in Applejack's barn attacking a series of crates. As a crate was opened Rainbow Dash would scoop up the contents, make a few comments and place them on work table that was on one side of the barn. When all the crates were opened Rainbow laid out everything in a row.

"Wow," she said. "Spitfire really came through for me."

"What do you mean, RD?" asked Applejack.

"I mean this is a lot more than she said she would let me have off-base," said Rainbow Dash. "Let's see. We've got two Mark I thrusters, two Mark II's, both with the 'C' upgrade, testing gear, a mounting rack and a full power testing frame."

"What are we gonna do with all of this stuff?" asked Applejack.

"Well, first off, you get the frame set up and I'll get the thrusters cleaned up and ready for use," said Rainbow Dash.

"And after that?" asked Applejack who was already getting out some tools.

"Then," said Rainbow Dash, "we see if an earth pony can fly." AJ said nothing, she just smiled and got to work assembling the frame. Which, fortunately, came with a full set of instructions. Soon, a sturdy frame had been assembled and bolted to the floor. Rainbow Dash had laid out an impressive set of meters and measuring devices on the workbench. Beside those were the narrow lines of two Mark I thrusters along with a pair of the double-pronged Mark II's.

"Well, Rainbow," said Applejack, as she tightened the last bolt. "Ah reckon this thing is about as solid as it can be. What now?"

"Okay," said Rainbow Dash. "Next thing we do is to get you secured into the testing frame. That way, if it turns out that you can power a thruster, you won't get splattered into a wall."

"Okay, well, Ah did line it up like you said, with the long ends toward the doors," said Applejack. "Where do you want me to stand?"

Rainbow centered her friend in the frame, and began to wrap padded lengths of solid metal around AJ's barrel, over her shoulders, across her chest and along her back and underside. The bars had been shaped to fit over the curves of a mare, but not the strong and full curvature of an earth pony mare. As Rainbow bolted the pieces of the frame together around Applejack, the secured lengths pressed tightly into the orange mare, causing her to gasp slightly.

"Dang, RD, ya think you've got me trussed up tight enough here?" asked Applejack.

"Gotta make sure you're fully secured," said Rainbow Dash, focusing on making sure everything was good and solid. "I'd never forgive myself if something bad happened to you. Now, I need you try to break loose, to test the frame. Go as hard as you can, and really try to break free."

"All right," said Applejack. For the next five minutes Applejack focused all her strength on trying to break out of the steel harness bolted around her body. She bucked, she kicked, she stomped and even bit. But after five minutes, even Applejack knew she wasn't going to break free through main strength. Which also meant nothing, like a thruster, was going to break her free by accident.

"Looks like ya got me," said Applejack, sweating and breathing deeply from the exertion. "Ah'm not getting outta this thing until you let me out."

"Ya," was all Rainbow Dash said, as she took in her friend who was firmly attached to the test frame. The play of soft muscle against rigid metal fascinated her. "Let me get you something to drink and give you a bit of a rub down before we go further," said Rainbow, getting a water bottle. She held it up to Applejack's mouth, while running a wing in circles down Applejack's smooth muscles, cooling and rubbing them. Dash's face was unreadable as she watered and stroked her friend.

"Um, Dash?" asked Applejack. As she noticed the strange look on Rainbow Dash's face Applejack realized just how completely she had put herself into Rainbow's hooves. She had seen similar looks directed at her by a few stallions in town on occasion while pulling her cart to market. If Rainbow wanted to do something to her there was almost nothing she could do about it. As she contemplated whether or not that would be a good thing, Dash's hoof replaced her wing in making long slow strokes down Applejack's flank. "Dash, you okay there, sugarcube?"

"Ya, I'm doing great," said Dash, with an odd distracted tone in her voice. Dash wasn't looking Applejack in the face at all. Instead, she seemed to be fascinated with her hoof as it passed down Applejack's side, circled her cutie mark and then began to slide toward her inner thigh.

"DASH!" yelled Applejack, as she tried to buck Rainbow's hoof away. The frame holding Applejack didn't budge a smidgen, but the sudden yell snapped Dash's attention back up to her friend's face.

"Oh, hell," said Rainbow Dash, as she whipped her hoof back about an inch before there would have been some serious consequences. "I'm sorry, AJ. It's just I've never seen or thought of you like this and well...you're kinda hot in a harness."

"Shoot," said Applejack, blushing. "Tell ya what, we get up into the sky and afterwards, well, maybe we'll see about that."

"Cool," said Rainbow Dash with a smile, as she walked over to the bench and picked up a Mark II unit. "Okay, you know what comes next?"

"Ya," said Applejack, looking over to Rainbow "You're gonna put that into me."

"Yup, close your eyes for me, AJ."

"Um, okay," said Applejack, even as she complied.

"Okay, think about me," said Dash, softly. "Touching you down there. Slowly stroking, gently finding that really good spot."

"Ah...ya," said Applejack, her voice going a little husky. She could picture herself captured in the frame, her best friend slowly kindling her desire.

"Picture me stroking you, rubbing you," purred Rainbow Dash, even as she intently studied Applejack's orange folds. "Helping you feel good, making it awesome."

"Ah can see it," said Applejack, and her folds began to moisten at the imagery her Dash was giving her. Thinking about how much she trusted her friend to take good care of her and her needs.

"Now," said Dash, seeing the moisture beginning to grow, "imagine yourself being completely filled." With that, Rainbow Dash slowly but firmly inserted the lubricated prongs of the Mark II into Applejack's moistening marehood.

"WHOA NELLY!" exhaled Applejack explosively, as the prongs filled her ass and pussy. Dash could see her friend's muscles working at the twin probes, trying to flex herself against the intruders in order to work the most enjoyment out of them. The test frame creaked as Applejack began to work herself to orgasm.

"AJ, stop," said Dash, knowing that if Applejack came, the test would fail before it had even begun. But Applejack wasn't stopping. Her world had narrowed down to the twin shafts filling her, and the fantasy Dash had painted for her. Rainbow Dash began to look around frantically for something, anything, to distract Applejack from what was obviously going to be an epic orgasm. Dash's eyes lit on a leather harness strap lying nearby.

"STOP!" Dash shouted, even as she brought the strap down as hard as she could onto Applejack's cutie mark.

"Aaah!" yelled Applejack, as her eyes shot open. The pain of the strike had pulled her out of the building spiral to orgasm. "What in the hay did you do that for?"

"You can't come yet, AJ," said Dash, keeping the strap nearby. She could see AJ's muscle still undulating, still trying to work against the thruster probes. "I'm sorry but if you come, the thruster only gets one massive burst of power and then nothing. You've got to control it. Ride the edge of it."

"Ah, right," said Applejack, nodding, and fought down the furious need for release. "I get ya."

"Damn, yeah, looks like you do," said Dash, impressed at how quickly her friend had been able to pull herself back from the brink. "Okay, the unit is in. Now to secure it." With that she pushed a small knob on the device. In the space of a few seconds, silvery metal flowed out from the device, wrapping around Applejack's hips, securing the thruster in place.

It also wrapped about six inches up Applejack's dock, and forced her tail up into a proud, vertical flag out of the way of the unit's exhaust. Applejack said nothing, only grunting a little as the probes were pulled that much further into her as the unit secured itself to her body.

"Okay, Applejack, I've got the unit preset for a thirty second, five percent power test," said Rainbow Dash. "Um, you doing okay there?"

Applejack looked around at her friend through half-lidded eyes. "RD, you've got my body locked into a metal harness Ah can't break free of, and you've filled my ass and my pussy. And even if Ah wanted to, Ah can't get either of those things out of me, except by your say-so. Oh, and you whipped me in order to control me." Rainbow Dash started to stammer an apology but Applejack pressed on saying, "And you've done it all to me, to help make a dream real. Ya, Ah'm good. Let's do this."

"Thanks, AJ," said Dash. "Okay, here we go. Activating Mode One." With that, she pushed a button on the remote control unit, and the thruster activated itself, the unit's probes individually vibrating and slowly rotating within their prisons of velvet flesh. To say Applejack was stimulated would be like saying water was wet, so the thruster was easily able to gather the generated power of lust and sexual desire, that it created in this first mode of operation. A howl of noise began to rise from unit as it swiftly spun up to power.

"Looking good, AJ!" yelled Dash over the noise. "Activating Mode Two in 3...2...1." As she said the final number, Rainbow Dash pushed the button that activated the Mark II Thruster at five percent power. What happened next was something beyond anything either pony had anticipated.

A lambent cone of force emerged from the thruster. Five feet behind the earth pony, that glowing, translucent force suddenly ignited in a blazing stream of flame going another fifteen back and out the thankfully open barn door. The power of the blazing energy emerging from the thruster drove Applejack forward with massive force, and if the frame she was attached to had even been one iota weaker, things might have gone very, very badly.

But, the frame held, and all that happened was Applejack grunted heavily as she forced air into her lungs against the pressure of the test frame's harness. Thirty seconds later the thruster ended it's preset test period and shut down. A sudden silence echoed through the barn even as the smell of smoke and singed everything rose in the building. Applejack slumped limply, held up only by the harness that kept her in place. Rainbow Dash looked from her friend, to the long scorch mark along the barn floor, and said in a quiet, reverent voice,

"In Celestia's name, Applejack. What have we done?"

Applejack didn't answer, content to simply rest in the grip of the rigid harness while she caught her breath. That rapidly changed as she heard a querulous voice call out from the house.

"Applejack? You out there? And what in tarnation was that goldurned racket?"

"Rainbow," said Applejack, her head snapping up as she recognized Granny Smith's voice. "Quick, get me outta this thing, fast."

"Right," said Rainbow Dash, grabbing a wrench in her wing. She began to struggle against one of the bolts. In vain. "We got a problem, Applejack. These bolts are actually bent."

"I'm stuck in this thing?" demanded Applejack. "At least get that...thing, out of my plot and tailhole. Hurry, before Granny gets here." Dropping the wrench, Rainbow moved to her friend's abused ass and pressed the stud to release the straps meant to prevent a thruster from accidentally falling out. Nothing happened. Rainbow Dash pressed the stud again. Still nothing.

"Hurry up, Rainbow," said Applejack. "Granny is gonna be here any second now."

"It won't release," snapped Rainbow Dash. "It's still cycling down." Despite that, the pegasus began to push and pull on the thruster, trying to convince it to release its grip on her friend. All she managed to do though, was to cause the probes of the thruster to work about an inch or so in, and out, of Applejack's now very sensitive intimate openings.

"Aah, Rainbow!" gasped out Applejack, as pleasure rocked her body, just as Granny Smith rounded the corner.

"Jes' what kinda shenanigans are you two up too?" asked Granny, as she took in the scene before her.

"Granny Smith!" exclaimed Rainbow Dash. "It's not what it looks like!" Even as she said the words, Dash realized what it had to look like. She had one hoof pushing what was basically a double plug dildo into her friend, who was trapped in an inescapable steel bondage harness and had just called out Dash's name in ecstasy.

"Young'n," said Granny Smith. "What it looks like is that you've got mah granddaughter harnessed up somethin' fierce, and yer givin' her the old double plow."

"Granny," said Applejack, in as even a tone as possible, which is to say, not very even at all. "It's okay, Dash was helping me. This thing in me, is gonna help put an Apple in the sky."

"Dearie," said Granny, as she walked up beside Applejack. "Ah'm sorry to have embarrassed ya, but ya don't need to come up with a whopper like that to explain what you and yer mare-friend are doin'. Ah may be old, but Ah've always known you two would be special friends."

"Ah'm not lying, Granny," said Applejack. "Rainbow has an idea to help me fly."

"So that's what you young folks are callin' it these days." said Granny Smith.

"Granny Smith," said Rainbow Dash. "Ma'am, I can prove it to you."

"How's that now?" asked Granny.

"I'll let you try this out so you can see that it's for helping AJ fly," said Rainbow Dash. "I've got a spare one over on the bench."

"Dash," whispered Applejack. "Are you crazy? One of those things will put Granny through a wall."

"Don't worry about it," Rainbow whispered back. "You know what these things are powered by and how old Granny Smith is. I'd be surprised if it moved her an inch AND it will show her I wasn't…."

"Taking advantage of a mare you have 'trussed up'," supplied Applejack, with a grin.

"Ya."

"Well, let's git 'er done then," said Granny Smith, from right beside the pair. "There may be snow on mah roof, but it don't mean there ain't a fire in the kitchen."

"AH!" yelled Rainbow Dash, surprised at Granny being so close. Then, gathering her composure said, "Um, okay Granny Smith, just hold tight onto Applejack and I'll get it set up." Rainbow Dash went over, grabbed the other Mark II and lubed it up. The elderly mare was braced against her granddaughter waiting with one eyebrow raised.

"You treat an old mare nice, ya hear," said Granny Smith.

"Yes Ma'am," said Rainbow Dash, even as she slid the thruster into Granny.

"Ohhh," breathed the old mare. "You did that right nice. Oh my, that feels good." Rainbow Dash smiled a bit as she reached over and grabbed the control unit.

"Here we go, Granny," she said. "Activating Mode One."

"That's kinda nice too…feels sorta tingly...Ya know, Ah haven't felt like this since-"

"Activating Mode Two."

"Taaaaaa **RRRRRRRRRRRRRRRRRRRRRRRN** ation!" Granny exclaimed as the thruster activated. If it wasn't for Applejack literally being a part of the testing frame and holding onto Granny, the unexpected five second blast of thrust might have put Granny through a hillside. As it was, the force of the twenty foot long cone of flame nearly tore Granny Smith out of AJ's hooves. But both mares held on, and five seconds later an utterly dumbfounded Rainbow Dash was rushing up to the two earth pony mares, as the thruster shut down.

"OHMYGOSH, OHMYGOSH, OHMYGOSH," exclaimed Rainbow Dash, in rapidfire concern for Granny. "Are you okay?"

"Whoowee, Rainbow Apple," said Granny Smith. "You _do_ know how to treat a mare nice. Welp, you convinced me, and Ah'll leave ya to it. Jest make sure ya'll clean up behind yerselves afterward." With that Granny began to walk away with a pronounced sway in her hips.

"Um, Granny Smith," called Rainbow Dash, after the elderly mare. "My name's Rainbow Dash. Not Apple."

"Dearie," said Granny Smith. "As long as you are _with_ an Apple, you _are_ an Apple. Welcome to the family." With that Granny sashayed out of the barn like a mare half her age, as the two younger mares looked on, barely believing their eyes.

"So, Rainbow _Apple_ ," said Applejack, with a grin "The hacksaw is over there on the wall if you feel like getting me out of this anytime soon." She bucked a bit against the harness that still held her captive, by way of emphasis.

"Oh, right," said Dash, as she headed over to the saw. "We've got a lot of work to do and not a whole lot of time to do it. But Applejack...I think it's gonna work. I think by this time next week, you are gonna fly!"


	2. Chapter 2

In the week following the drive test that had proven that earth ponies could power a thruster, the two friends had taken over one of the outbuildings of Sweet Apple Acres, and had moved all of their equipment to it. After the massive jet of flame the drive test had created, Granny Smith had insisted Applejack and Rainbow Dash move their work to a less...frequented area of the farm. To that end, all of their gear and equipment had been moved over to the new building. Over which Rainbow had proudly put up a sign saying, "Apple Aerospace."

"So, RD," said Applejack. "Or should Ah call you RA now, Rainbow Apple?"

"Ha ha," said Rainbow Dash. "Very funny. I respect Granny way too much to argue with her about her calling me an Apple. I mean, she's letting us use this building and she even gave you the week off. She's pretty awesome."

"Speaking of Granny," said Applejack. "Did you manage to get that other unit back from her?"

"Yah," said Rainbow Dash, colouring slightly. "She gave it back to me, yesterday. Said something about 'new-fangled plows' when she did."

"So, RD," said Applejack, with a slight chuckle. "We've been working on stuff all week now. What's the plan?"

"Okay, Applejack," said Rainbow Dash, as spread out a somewhat crude diagram. "We've reshaped the test frame harness so it will fit you better, and we've made one, just as solid, for me. The harnesses each have a spar running along their length. Yours is along the back and mine is along my belly. The spars lock together, making you and me a single flight element -"

"Um, Rainbow," interjected Applejack. "We already have Granny thinking we are some kinda kinky bondage couple. Ah mean, Ah like you and all, and maybe we will have a little fun if things go right. But we do this and everypony, and Ah do mean everypony, is gonna assume we are together."

"Ya, about that," said Rainbow Dash, as she reached a wing into a nearby bag and pulled out a bridle with fairly large bit attached to it.

"What. The buck. Is that?" demanded Applejack.

"Ah, well, I thought you would want direct control of your thruster," said Rainbow Dash. "The bit is a throttle control. The bridle will keep it in place, so all you have to do is to roll the bit in your teeth, and you can set the thruster output to whatever you like."

"Dash. It's a bit. And a bridle," said Applejack, with more than a little bite in her words. "And where did you even get that?"

"Well…." said Rainbow Dash, who sighed and then pressed on. "Granny told Big Mac about us, and he told Fluttershy, and she told Twilight. So, when I went to Twilight to get something so you could have more control…she already had that waiting for me. And one for me too. Don't forget, Twilight has been tweaking these things for awhile now, so I'm guessing she was planning for these to go with the new Mark III unit."

"So, everypony already figures we're together. Well, as long as you got a bridle too," said Applejack, who shook her head and then smiled. "If everypony is figuring we're a couple now, we might as well match. C'mon, we better make sure they fit." With that Rainbow Dash fitted the bit and bridle to her friend and Applejack did the same to Rainbow Dash. Both fit perfectly. The bits attached to the bridles were not pulled to the back of the mouth as expected, but instead, sat in the middle area of the mouth. This made them relatively easy to speak around. As well, what had first been taken for as reins were actually the control runs from the bridle to the thruster unit.

"You know, Dash," said Applejack, around her throttle bit. "You actually look kinda good yourself, wearing a bridle. Sort of a controlled strength sort of look. Looks good on ya." Rainbow Dash blushed a bit at the unexpected compliment. "So, we good to go for tonight?"

"Ya," said Rainbow Dash, accepting the change of topic. "Big Mac will be here just after dinner to help us harness urk—" Rainbow's words were cut off as Applejack grabbed the control runs, and using them like the reins they resembled, took control of the bridle and bit in Rainbow's mouth.

"Ah still owe you for all that stuff you did, when you had me bolted into that metal harness the first time," whispered Applejack into Rainbow Dash's ear. "And there are _hours_ until Big Mac gets here. Time to see just how awesome you are." With that, she pulled her willing mare friend toward the nest of cushions they kept in the back of the building for naps.

-==========00000==========-

Hours later, after the sun had set, Big Mac was tightening the final bolts that secured Rainbow "Apple" into her harness. "So, why you all doing this at night?" the roan stallion asked.

"I want everypony to see how awesome your sister is," said Rainbow, as Applejack grinned. "Seriously, I can't believe how much power she was able to give to a thruster unit. And the flame! That was totally cool."

"Don't worry none about the orchard, Mac," said Applejack. "The plan is for Rainbow to use her unit to get us up into the air. Once we are high enough above the trees, Ah'll fire up my unit and well, we blast off."

"So that's why you had me make an oversized scooter and a jump ramp," said Big Mac.

"Sure is," said Rainbow Dash. "At the start, I'm going to be flying us both, so the scooter and jump ramp will be a big help. Plus, it will look awesome." Dash did a few tugs and pulls on her harness. It wasn't going to come off on its own any more than Applejack's was. "Okay, Applejack, time to see if you can fly."

With that Applejack stood on the scooter and braced herself. Then, using a small stool, Rainbow Dash climbed up on top of her friend. Moving carefully, she matched tabs in her harness to slots in Applejack's. Once they met and seated, Big Mac moved in and bolted the two harnesses together. For better or worse, Applejack and Rainbow Dash were now a single piece of steel, flesh and fur.

"All secure?" asked Big Mac.

"Yup," said Applejack and Rainbow Dash at the same time.

"Okay, Big Mac," said Rainbow Dash. "You get to have some fun now."

"Eyup," said Big Mac in an oddly pensive voice. Big Mac went over to a workbench and returned with a lubricated Mark II thruster. He slid it back and forth over Applejack's tailhole and pussy, getting some of the lubricant onto his sister, before sliding home the twin plugs of the Mark II.

"Ahhh," Applejack breathed out explosively. "Ah don't think Ah will ever get used to that thing going in. Hey, Mac, aren't you gonna lock it in place?

"Eyup," said Mac, as he gathered up the other thruster unit, and repeated the process of insertion on Rainbow Dash. Then, to both mares surprise, instead of securing the thruster units, Big Mac began to work the double prongs of the two units in and out of the harnessed duo. Applejack and Rainbow Dash both began to moan and shudder as the collector shafts of the thrusters slid in and out of their intimate passages.

"M-Mac, what are you doing?" asked Rainbow Dash desperately. The stimulation Big Mac was working on her was swiftly building her to climax. She could feel that delicious heat building inside her and she knew Applejack had to be feeling the same. "You've g-got to s-s-stop."

"And why would Ah want to do that?" asked Big Mac seriously. "Seems to me that, if Ah get either of you to come, y'all can't go off on this dang fool thing and get mah sister's neck broke."

"M-Mac, please," begged Applejack, her own voice trembling with her nearness to orgasm. "Let me have my dream. Let me fly." Big Mac looked at his sister and nodded.

"You promise me, Dash," said Big Mac, suddenly stopping his attempt to drive both mares to orgasm. "You promise me, that no matter what, mah sister makes it back. Safe and sound. If you can't do that, Ah'll have to stop you." He tapped Dash's thruster to emphasize his point.

"I swear, Mac," said Rainbow Dash. "If Applejack doesn't make it home it will be because I'm already dead and gone. She makes it home, no matter what. I swear it."

"Good enough," said Mac, pressing the button on both thrusters that caused them to lock onto both mares. The harness modifications also meant that the thrusters attached to their harnesses as well, making the two brave mares into a single, double-driven unit.

"Thanks, Mac," said Applejack. "Ah know you worry about me, but this is something I need to do."

"Ah'm sorry, AJ," said Big Mac, as he began to wheel the pair out to the runway they had prepared. "Ah don't think Ah could stand losing you."

"It'll be okay, Mac," said Applejack. "Ah've even got a parachute in this rig just in case everything goes pear shaped. Now, go get clear and send a message to Twi letting her know we are getting ready to launch." Big Mac said nothing, merely nodding as he finished positioning the modified scooter carrying Applejack and Rainbow Dash at the end of the long straight stretch that ended at a jump ramp.

Big Mac put a forehoof on Applejack's shoulder and said, "Fly safe, both of you." Then he scrambled off to the side.

"Okay, Applejack," said Rainbow Dash. "You ready?

"Let's go already," said Applejack with a grin.

"All right, AJ. Just like we planned," said Rainbow Dash. "I'll get us up to a few hundred feet, and when I put us into a second climb, you light off your unit and we see what happens." Rainbow Dash took the bit in her mouth and triggered her thruster, its power driving the linked duo down the runway. As acceleration took hold, the wheels on the scooter turned faster and faster, and as their squealing cry and that of the thruster rose to a banshee wail, the intrepid duo reached the launch ramp.

As they were hurtled into the air Rainbow Dash extended her wings, letting out a grunt of effort as her frame took up the combined weight of both ponies. The blue pegasus kept their flight as smooth and even as she could, slowly climbing in a classic "racetrack" pattern in order to stay over the farm. After a couple of minutes, Rainbow Dash pushed her control bit out to talk to her friend beneath her.

"Okay, Applejack," she said. "You ready?"

"Ah've been ready for this all my life," said Applejack. "Let's do this...together." With that, she drew her own control bit into her mouth.

"Together," said Rainbow Dash, and as she angled her wings into a climb, she added more thruster power to maintain their attitude. Ten seconds later, Applejack activated her thruster…and all hell broke loose.

In the first few seconds, all that happened was a solid push of acceleration, as the greater power and stamina of an earth pony gave Applejack's thruster ten times the power of a pegasus driven thruster. But then Applejack's thruster interacted with Rainbow Dash's, and what would later be termed "The AppleDash Effect" manifested itself for the first time ever. It was expected that the thrusters would add their power together, but that isn't what happened. It was hoped that the thrusters would, perhaps, multiply their effects on each other. That didn't happen either.

Instead the thrusters added their power together, then that power folded back on itself, so that it multiplied itself...by itself. What was initially an extremely impressive four hundred wing power suddenly erupted into a mind-shattering, one hundred and sixty thousand wing power. Ponies suddenly looked up in astonishment and terror as a second sun suddenly dawned over Ponyville. The air was shattered by the rolling thunder of the two-hundred-foot-long jet of flame that was now strung out behind Applejack and Rainbow Dash. Against that titanic force, flesh and bone was a frail reed, and Rainbow Dash's wings were slammed against her sides.

With all aerodynamic control lost, the only guidance was provided directly by the thrusters themselves, and they continued to drive the duo upwards into what soon became a near-vertical climb. Applejack was lost to the glory of flight and the driving churn of the thruster insider her. For her part, Rainbow Dash realized the danger they were in, and used her pegasus magic to gather a bubble of air around them. She knew that at the rate they were climbing, the air would become too thin to breathe within seconds.

"Applejack!" screamed Rainbow Dash in her friend's ear, even as the sky turned black above them again. "You've got to slow down!" But Applejack didn't hear her, so lost was she in her internal world. It wasn't until thirty minutes later, as the air that Dash had trapped around them began to grow stale, that Applejack finally snapped back to reality.

"Sweet Murphy!" exclaimed Applejack, as she let off on her bit throttle and saw the very small and distant disc of Equestria. "We're higher than a kitty in the catnip. Why'd you let us get so high?"

"I didn't have a choice, Applejack," said Rainbow Dash. "I'm not sure what happened, but we went so fast I couldn't use my wings anymore. And, I think we're in real trouble."

"Why's that?"

"Because the air I pulled around us is running out," said Rainbow Dash. "And, if you haven't noticed, we've gone past the freaking moon! There's no air here. None at all. We need to get turned around, right now. But there is no air for me to push against to turn us."

"Okay, Dash," said Applejack. "Hold on. I'm gonna try something we use on the farm sometimes to get plows to turn." With that, Applejack throttled the thruster back up and began to rhythmically grunt. Rainbow suddenly realized that with every grunt Applejack made, their course shifted a few degrees. Slowly but surely the pair of pones turned around, to face their now very distant home.

"What did you do, Applejack?" asked Rainbow Dash. "That was pretty awesome."

"Pelvic floor muscles," said Applejack. "I used them to rock the thruster back and forth to get us turn, just like we rock a plow when we pull it to turn around, if it gets stuck a bit on the farm. We good now?"

"Nah, we're toast," said Rainbow Dash, despondently. "You turned us, but we are still headed away from Equestria and we've maybe got a couple of minutes of air left. Unless..." Rainbow Dash paused as she suddenly remembered her conversation with Spitfire on the very first day she had seen a thruster unit.

"Unless what, RD?"

"We've got one shot at this," said Rainbow Dash, suddenly energized. "I know you were at about eighty percent on your throttle, like me. We need to both go to full thrust and then..."

"Then, what?"

"Then we both need to come at the same time," said Dash. "The only thing that would give us a chance is what the Wonderbolts call 'flaring out.' One huge burst, to get us home."

"Okay, Dash, times a-wastin'," said Applejack, nodding. "Let's do it. 3...2...1...thruster on." With that, both mares activated their thrusters.

"AJ, go to full," grunted out Rainbow Dash a moment later, as she did her best to hold her orgasm at bay until the right moment.

"A-At full, now," gasped Applejack. "A-Ah'm close, RD. Call it out."

"R-Right," said Rainbow Dash. "O-On my call. 3...2...1...FULL THRUST!"

Both Applejack and Rainbow Dash cried out in ecstasy as they finally allowed themselves to give in to the siren song that the thruster units had been playing inside their bodies for so long. The units gleefully soaked up the surge of released lust and the duo suddenly disappeared in a coruscating rainbow, as the thrusters broke through an unknown barrier.

 _Elsewhere…_

 _"Warp trace!" cried out a voice. "Warp one, unknown configuration."_

 _"Point of origin?" asked a much calmer voice that held the tone of command._

 _"Two three eight, mark twelve. Distance puts it in the Epona Sector, sir," said the first voice. "Trace is gone, sir. Not much more than a warp burst."_

 _"Right. Seems like someone out there has made a breakthrough," said the second voice. "Let's welcome them to the neighborhood. Who do we have nearby?"_

 _"_ Enterprise _is in area studying gaseous anomalies, sir," said the first voice. Now in a much calmer tone._

 _"Right, send Picard a message giving him our best idea of the location," said the commanding voice. "Tell him to prepare for a First Contact situation."_

Two hours later, the search teams found Rainbow Dash and Applejack still linked together, half-asphyxiated and unconscious. Their desperate gamble had gotten them home just in time; but in the end, it was only the last minute addition of the parachute to Applejack's harness that had saved them both from a fatal impact.

"Are they going to be okay?" Twilight Sparkle asked Luna, who had spotted the falling duo and sent the rescue teams to the right area.

"I believe so," said Luna. "But one thing is certain. Those ponies have boldly gone where no pony has gone before."


End file.
